Wood Plastic Composite Products Research Articles

Sustainable WPC Production: A Novel Method Using Recycled High-Density Polyethylene and Wood Veneer

This research work is focused on the development of an alternative method for manufacturing Wood Plastic Composite (WPC) panels based on Wood Veneers (WVs) and High-Density Polyethylene (HDPE) through compression molding, which enhances the physical properties, particularly, water absorption and moisture content. The aim of the present research was to develop alternative panels to replace commercial ones, which are heavily affected by hot, humid climates. In this context, the study began with the design process, which consisted of the collection and processing of primary material, production of the additional components necessary for the manufacturing process, determination of the WV ratio, and preparation of the samples. Thereafter, physical and mechanical tests were carried out on WPC, HDPE (control), commercial gypsum boards (GBs), plywood (PW), and medium density fiberboard (MDF) samples. The results indicate that the method applied to manufacture the WPC samples improved physical properties, achieving a water uptake of less than 4% in both proportions of replacement tested, in contrast to commercial panels, which reached values between 10% and 40%. In addition, a greater load capacity was achieved for lower thick elements.

Mechanical performance assessment of sustainable coal plastic composite building materials

This paper presents a study for developing a high filler content coal plastic composite (CPC) for use in building and construction applications as a substitute for the state-of-the-art wood-plastic composites (WPCs). The influence of coal type (bituminous, sub-bituminous) and content (up to 70 wt%) on the mechanical performance was characterized and compared with predominant commercially available WPC products. SEM micrographs revealed good adhesion between coal and the polymer at the interface with less porosity than WPCs. Additionally, particle fracture and particle pull-out failure mechanisms were evident in the SEM micrographs, with the latter being more dominant. DSC thermal analyses revealed potential chemical reactions between the coal and HDPE interfaces, resulting in enhanced composite performance. Results indicate the tensile strength for CPC material had inverse proportionality with coal content. Despite the reduction, tensile strength for CPC with 60 wt% bituminous coal was not significantly different from a typical WPC formulation. Flexural strength increased to a maximum value, at 60 wt% for bituminous coal and 50 wt% for sub-bituminous coal, followed by a decrease. CPC with 60 wt% bituminous coal possessed higher flexural strength and, in some cases, comparable flexural modulus as compared to WPC products. Flexural properties indicated that a composite deck made from the CPC material could meet or exceed the loading and deflection requirements for decking boards. FEA models indicated that a hollow deck profile would potentially have a better load-deflection curve with less localized stresses compared to common decking board profiled sections.

Effect of Coupling Treatment on Interfacial Bonding Properties of Wood Veneer/Wood Flour–Polyvinyl Chloride Composites with Sandwich Structure

Wood–plastic composites (WPCs) have received growing attention due to their good water resistance, environmental friendliness, and recyclability. For the application of WPCs in interior decoration and other high–value fields, it is necessary to preserve these characteristics whilst enhancing their mechanical properties and surface aesthetics. In this study, we used a sandwich structure and four interface modifiers to prepare wood veneer/wood flour–polyvinyl chloride composites (WWPVCs). The results revealed that the WWPVCs treated with a silane coupling agent exhibited superior interfacial bonding and mechanical properties compared to those obtained using other interface modifiers. The interfacial bonding strength of the treated sample reached 1.22 MPa, which was 122% higher than that of the untreated sample. In addition, the wood failure ratio of the optimal sample reached 80%. Furthermore, the dipping–peeling length was found to be shorter than those achieved using other interface modifiers after tests at 63 and 100 °C, indicating that the material treated using the silane coupling agent exhibits an excellent resistance to moisture and heat. Notably, silane coupling agents are easily prepared as solvent–based modifiers, and they do not release harmful gases (e.g., formaldehyde), thereby rendering them highly effective in the preparation of environmentally friendly WPC products.

Utilization of Torrefied and Non-Torrefied Short Rotation Willow in Wood-Plastic Composites.

The torrefaction process is widely used in the energy field, but the characteristics of the torrefied wood also have positive effects on the production of wood plastic composites. In this study, short-rotation shrub willow was torrefied at 225 and 300 °C and incorporated into polypropylene composites filled with changing levels of weight percent (wt%) of non-torrefied and torrefied (5, 15, 25, and 40 wt%) wood. Nine different formulations were extruded for mechanical, thermal, and water absorption properties. The tensile properties of composites were not affected by any level of torrefaction, while higher flexure properties were in favor of lower wt% of torrefied wood. The slowest rate of thermal degradation was confirmed for the highest wt% of torrefied wood with a torrefaction temperature of 300 °C. In contrast, the presence of torrefied wood in composites did not show a difference in crystallization or melting temperatures. The most noticeable contribution of torrefaction temperature and wt% was found for water-absorbing properties, where the higher torrefaction temperature and largest wt% of torrefied wood in the composite resulted in decreased water uptake.

Using furniture factory waste sawdust in wood-plastic composite production and prototype sample production

This study investigated the possibility of furniture factory waste sawdust (FFWS) utilization in polypropylene (PP) composites and producing furniture support leg prototypes. Test samples were manufactured using a single screw extruder and injection molding machine utilizing 10, 15, 20, 25, 30, and 35% by weight of FFWS and 0% or 3% maleated polypropylene (MAPP). Selected mechanical and physical properties of manufactured samples were determined. The presence of FFWS and MAPP significantly improved mechanical properties compared to neat PP. The higher FFWS amount increased the flexural strength, flexural modulus, tensile modulus, impact resistance, and density. Tensile strength and elongation at break decreased with filler amount, but the addition of MAPP caused a dramatic increase in tensile strength. In addition, flexural strength, flexural modulus, tensile strength, elasticity modulus, and density values of the composites containing MAPP had higher values than the ones without MAPP. However, impact resistance and elongation at break values were slightly decreased with the addition of MAPP. Optimization results showed that formulation mixtures containing 20% filler and 3% MAPP fit best for prototype furniture legs manufacturing.

Comparative study of some properties of wood plastic composite materials produced with polyethylene, wood flour, and glass flour

Wood flour is the most common filler used in the production of wood plastic composite (WPC) materials. In scientific studies on this subject, wood flours obtained from different trees and fillers obtained from different annual plants are used. In addition, some mineral-based fillers are also used in materials made of plastic. In this study, a low-density polyethylene polymer obtained from recycling was used as the matrix. Larch wood flour and glass flour obtained by grinding soft drink bottles were used as fillers. Composite boards were produced using 60% polymer as the matrix, along with wood flour and glass flour in varying proportions. The density, flexural strength, flexural modulus, tensile strength, tensile modulus, elongation at break, and hardness values of the produced composites were determined. Based on the data obtained, the density increased with the addition of wood flour and glass flour as fillers, and the density-increasing effect of the glass flour was higher than that of the wood flour. Compared to the control samples, it was determined that the bending strength and elongation at break of the experimental groups decreased, and the flexural modulus and tensile modulus increased in the experimental samples using wood flour and glass flour.

POTENTIALS OF SAWDUST AND DISPOSED WATER SACHET WASTES FOR WOOD PLASTIC COMPOSITE PRODUCTION

The study investigated the potential of sawdust and disposed water plastics for the production of wood plastic composite. The sawdust was obtained from the plank market in Yola, while, the water sachets were hand-picked within the Modibbo Adama University premises. The gathered sawdust were sieved into 1.0 and 2.0 mm particle sizes, thoroughly mixed with already melted water sachet plastics at a ratio of 1:25 (100: 2500 ml) and 1:30 (100:3000 ml) respectively,. The mixtures were heated at (105.20 C,) and then filled into an already constructed oiled Aluminum mold of size 1.5 x 6 x 15 cm. Pressure was applied for two hours to compress the composite before removal from the mold. The samples were then trimmed according to sample size requirement, for mechanical and physical property properties tests. The results revealed that, the plastic composite produced from 2mm sawdust particles and mixed at ratio of 1:25 has the highest mean hardness (14.99 ± 3.54 MPa), The mean highest impact strength (1.24 ± 0.12 J) was obtained in the sample with particle size 1 mm and plastic ratio of 1:30, while, the highest mean water absorption percentage (2.27 ± 0.132 ) was obtained in particle size 2 mm and plastic ratio of 1:25.The Analysis of variance conducted shows that, sawdust particle size and mixing ratio had significant effect on both physical and mechanical properties of the produced plastic composite (p < 0.05). The study had demonstrated that the use of disposed sachet water plastics and sawdust waste

Mechanical properties of wood-plastic composites produced with recycled polyethylene, used Tetra Pak® boxes, and wood flour

The recycling industry has developed rapidly in recent years. Paper, plastic, glass, and metals are the most recycled materials. In this study, composite boards were produced using recycled polyethylene (R-PE) mixed with used Tetra Pak® boxes (TPBs) and pine wood flour (PWF) as fillers. The ratios of TPB to wood flour used in study were 0%, 10%, 20%, 30%, and 40%. Six test groups of composites were prepared. For each group, four composite boards of dimensions 4 × 180 × 220 mm3 were produced. Some of the mechanical properties of the produced boards, such as the flexural strength, flexural modulus, tensile strength, tensile modulus, elongation at break, and Shore D hardness, were determined. The data obtained showed that the flexural modulus, tensile modulus, and density increased with the wood flour content. However, the flexural strength, tensile strength, and elongation at break decreased as the wood flour content was increased. As a result, it can be said that TPBs could be used as a filler instead of wood flour in the production of wood-plastic composites.

Tropik ağaç türü olan dahoma (Piptadeniastrum africanum) odununun odun plastik kompozit üretiminde kullanımı

Bu çalışma kapsamında profil çekme makinesinden çıkan atık dahoma odun ununun polipropilen (PP) bazlı odun plastik kompozit üretiminde dolgu maddesi olarak kullanımının kompozit malzemelerin mekanik ve morfolojik özellikleri üzerine etkileri incelenmiştir. Atık odun unları fabrikadan alındığı gibi ve dört farklı oranda (%0, %15, %30 ve %45) kullanılmıştır. Atık odun unlarının boyut analizi gerçekleştirilmiştir. Uyumlaştırıcı olarak %3 oranında maleik anhidrit polipropilen (MAPP) ve yağlayıcı olarak %3 parafin wax kullanılmıştır. Elde edilen sonuçlar neticesinde odun ununun eklenmesi ile çekme ve darbe direnci değerlerinde hafif dalgalanmalar gözlemlense de genel olarak mekanik değerlerde iyileşmeler belirlenmiştir. Odun ununun katılım oranının artması ile çekmede elastikiyet modülü, eğilme direnci ve eğilmede elastikiyet modülü özellikleri iyileşmiştir. Kopmada uzama değerlerinde ise keskin bir düşüş gözlemlenmiştir. Morfolojik özellikleri incelendiğinde odun ununun homojen bir şekilde polimer matris içerisinde dağılım gösterdiği ve polimer matrisin dolgu maddelerinin etrafını iyice sardığı ve iyi bir arayüz etkileşiminin olduğu gözlemlenmiştir. Sonuç olarak, atık dahoma odun unlarının odun plastik kompozit üretiminde değerlendirilebileceği kanaatine varılmıştır.

Study on the Direct Transformation of Milk Bottle and Wood into Wood–Plastic Composite through Injection Molding

Plastic has transformed the world; however, it generates a huge amount of waste plastics. It is well evident that, if urgent action is not undertaken on plastic pollution, it will pose threats to not only the environment, but also human life. Just simply discarding waste plastics will result in wasting a lot of valuable materials that could be recycled. Recently, the use of waste plastics has been considered for producing wood plastic composites (WPCs), which are superior to normal wood. Waste plastics are pelletized using an extruder and are then subjected to injection molding. In this study, investigations were carried out to determine the possibility of producing WPCs without the palletization of waste plastic to turn WPC production into a shorter, simple, and easy-to-achieve process. Here, a waste milk bottle, a familiar single-use plastic, was picked as a case study. Waste plastic granules and wood particles were mixed and directly injection molded to produce valuable WPCs. The water absorption of WPCs with 20% wood is 0.35%, and this increased to 0.37% when wood content was increased to 40%. The tensile strength at yield, elongation at break, and impact strength of WPCs with 20% wood content are 19.54 MPa, 5.21%, and 33.92 KJ/m2, respectively, whereas it was 17.23 MPa, 4.05%, and 26.61 KJ/m2 for the WPCs with 40% wood content. This process can be a potential solution for two problematic wastes at the same time.

Recent progresses in wood-plastic composites: Pre-processing treatments, manufacturing techniques, recyclability and eco-friendly assessment

Wood-plastic composites (WPCs) have shown promising domestic and industrial applications. Both virgin and waste materials have been used as matrix and reinforcement materials in WPCs manufacturing which enhances the eco-efficiency of WPCs products. This study presents a comprehensive review on the WPCs manufacturing techniques including pre-processing of the composite ingredients and post-processing of the WPCs products. Three main types of pre-processing techniques have been discussed; chemical, mechanical, and thermal treatments. Conventional manufacturing techniques of WPCs such as extrusion molding, injection molding, compression molding, stir casting, and hot-press method have been presented. In addition, advanced manufacturing techniques such as selective laser sintering have been briefly discussed. The recycling of WPC is also discussed. Eco-friendly assessment of WPCs has been also introduced. Important conclusions and the future research trends have been mentioned in the end of the article.

Flammability and thermal stability of thermoplastic-based composites filled with natural carbon

This investigation characterized flammability and thermal stability for a novel sustainable composite engineered for use in building applications. Flammability and thermal stability of coal plastic composites composed of coal (40–60 wt.%) and high-density polyethylene were compared to commercial wood–plastic composites. Pyrolysis thermogravimetric analysis results indicated that coal plastic composites possessed a single-step decomposition and higher char residue, while wood–plastic composites had two-step decomposition, with the first peak occurring at much lower temperatures. Thermogravimetric analyses in air suggest coal plastic composites, compared to wood–plastic composites and neat high-density polyethylene, were more thermally stable. Flash ignition temperatures for coal plastic composites were higher than high-density polyethylene and wood–plastic composites, while self-ignition temperatures were in the same range as wood–plastic composites. Rate of burning data indicated coal plastic composites were slower burning than wood–plastic composites, with increasing coal content slowing burning rate by 19.9%–27.6%. Cone calorimeter testing showed 27% and 59% reduction in total heat release and total smoke release as coal content increased while coal plastic composite with 60 wt.% coal possessed lower overall flammability in comparison with predominant commercially available wood–plastic composite products. Coal improved composite overall thermal stability and flammability by acting as char former and foaming agent.

Recycling end-of-life WPC products into ultra-high-filled, high-performance wood fiber/polyethylene composites: a sustainable strategy for clean and cyclic processing in the WPC industry

As “green” composites, recycling end-of-life wood-plastic composites (WPCs) is crucial for sustainable and efficient resource utilization and carbon neutrality. In this study, waste WPC windows with 47.6 wt.% wood fiber (WF) were recycled as the polymer matrix and then reprocessed with waste WFs by extrusion into ultra-high-filled WF/polyethylene composites (UH-WPCs) using MAPE as a compatibilizer. The tensile and flexural moduli of all UH-WPCs with/without MAPE were higher than those of the waste WPCs. The MAPE-compatibilized UH-WPCs demonstrated improved water resistance, creep resistance, and dimensional stability. The tensile strength, tensile modulus, flexural strength, and flexural modulus of the UH-WPCs with 80 wt.% WF and 4 wt.% MAPE were 26.6%, 50.0%, 26.4%, and 87.9% higher than those of the waste WPCs, respectively. The presence of MAPE could improve the WF-matrix interfacial interaction and protect the WF from damage during reprocessing owing to the improved wettability and plasticization on WF. It is anticipated that the proposed strategy will provide a facile method to recycle end-of-life WPC products into high-performance composites at a low cost.

Production of Sugar Beet Pulp/LDPE Composites Using Compression Molding Method and Investigation of Some Properties

Aim of study: In this study, the effect of lignocellulosic filler and coupling agent amount on the physical and mechanical properties of produced sugar beet pulp/LDPE composites were researched.
 Material and methods: Wood-plastic composites were produced using compression molding method. The effect of lignocellulosic filler and coupling agent (maleic anhydride grafted polyethylene) amount on the physical (density and water uptake analyses) and mechanical (tensile strength, tensile modulus, elongation at break, flexural strength, flexural modulus, and impact strength) properties of composites were investigated.
 Main results: According to the obtained results, the rise in the amount of SBP were increased the density, tensile modulus, flexural strength, and flexural modulus while decreasing tensile strength, elongation at break, and impact strength of the resulting composites. Generally, the increase of coupling agent (MAPE) amount improved the composites properties except for impact strength and elongation at break.
 Highlights: Sugar beet pulp (SBP) can be successfully used as an alternative lignocellulosic filler in the wood plastic composite production.

Physico-mechanical properties and long-term creep behavior of wood-plastic composites for construction materials: Effect of water immersion times

The optimal formulation described by Srivabut C. et al. (2019) of 51.8 wt% rPP, 35.9 wt% RWF, 7.2 wt% CC, 3.9 wt% MAPP, 0.2 wt% UV stabilizer, and 1.0 wt% Lub was used in the study, it was shown to possess the best mechanical and physical properties for wood-plastic composites (WPCs). This formulation was used to investigate the mechanical and physical properties and effects of stress, temperature, and time on flexural creep with 35% of the ultimate flexural strength, after water immersion for various times. In addition, the time-stress superposition (TSS) principle was used to predict the lifetime for WPCs. The results showed that the mechanical properties generally decreased up to 40% with immersion time in which samples absorb water quickly in the first week, after which these absorption increases more slowly until the saturation point. This is most likely due to the increase of free OH groups in the composites and the long-term absorption, resulting the decrease of mechanical resistance of the WPCs. All of the WPC specimens experienced increased lightness and total color change, indicative of fading or lightening. The L* of the control sample had lower lightness than WPCs immersed for 1, 5, and 10 weeks. Also, the ∆E* in all cases increased with immersion time until 10 weeks. Almost no color change was observed in first week of immersion, after which it gradually increased. The creep behavior of WPCs was dependent on stress, temperature, and water immersion time, increasing with all of these. The master curve from time-stress superposition principle was in a good agreement with R2 of 87.45% for long-term creep. It was found that the lifetime predictions of WPC products exceeded 10 years for 3 MPa stress at 25 °C (control sample). However, the WPCs after 10 weeks of water immersion showed poorer performance, with lifetimes of the composite products under 3 and 15 MPa stress at 25 °C estimated to not reach 5 years.

FLAT-PRESSED WOOD PLASTIC COMPOSITES FROM COMMUNITY FOREST WOOD BARK AND RECYCLED POLYPROPYLENE: THE EFFECT OF PRESSING TEMPERATURE ON THE PHYSICAL, MECHANICAL, AND MORPHOLOGICAL PROPERTIES

The article describes a new idea related to the use of wood bark powder as a filler material in the production of wood plastic composites using flat-pressed method, based on its thermal stability and abundant availability, enabling replacing wood powder, which has been widely used. This research aims to study the effect of temperature on the physical, mechanical, and morphological properties of flat-pressed wood plastic composites made from Gmelina arborea bark and recycled polypropylene. A 40:60 mesh (5% moisture content) of G. arborea bark powder was mixed with recycled polypropylene (RPP) pellets with a weight ratio of 40:60 and a maleic anhydride (MAH) modifier as much as 5% of the weight of the RPP was added. Mixing the ingredients is done in a rotating blender for 15 minutes at a speed of 80 rpm until homogeneous. The mixture was heated at 175oC until the RPP pellets were completely melted and then cooled at room temperature. After that, the material mixture was made into powder and filtered, and then moulded in a steel plate mould at temperatures of 160, 165, and 170oC under a pressure of 30 kg/cm2 for 4 minutes with a target density of 1 g/cm3. Physical properties including density, moisture content, water absorption, thickness swelling, and volume shrinkage according to ASTM D570 standard were determined. Mechanical properties, such as modulus of elasticity (MOE) and modulus of rapture (MOR), referring to ASTM D7031 standard, and tensile strength parallel to panel length, referring to ASTM D638 standard, were also evaluated. In addition, composite morphology was also studied using scanning electron microscopy (SEM). The results showed that the increasing of pressing temperature had a significant effect on the improvement of moisture content, water absorption, thickness swelling, volume shrinkage, and MOR. MOR value increased by 34.12% when the pressing temperature increased form 160oC up to 170oC. Our method allows improving the physical and mechanical properties of wood bark plastic composites based on a pressing temperature of 170oC.

A Comprehensive Review on Process and Technological Aspects of Wood-Plastic Composites

This review deals with recent works on the process and technological aspects of wood-plastic composites (WPCs) manufacturing.WPCs relate to any composites that are built from wood and non-wood fibers and thermoplastic polymers. Recent progress relevant to wood-plastic composites has been reviewed in this article. The process and technological aspects of WPC, such as raw materials, fabrication, mechanical, physical, thermal, and morphological properties, were outlined comprehensively. The manufacturing process of WPCs is an important aspect of WPCs production. Manufacturing methods like compression molding and pultrusion have some limitations. Extrusion and injection molding processes are the most widely used in WPCs due to their effectiveness. Recent developments dealing with WPCs and the use of different kinds of nanofillers in WPCs have also been presented and discussed. Nanoclays are widely used as nanofillers in WPCs because they represent an eco-friendly, readily available in large quantity, and inexpensive filler. WPCs can be found in a wide range of applications from construction to the automotive industry.Keywords: additive manufacturing, adhesion, fabrication techniques, mechanical and physical properties, wood-plastic composites

Alien Wood Species as a Resource for Wood-Plastic Composites

Since invasive alien species are one of the main causes of biodiversity loss in the region and thus of changes in ecosystem services, it is important to find the best possible solution for their removal from nature and the best practice for their usability. The aim of the study was to investigate their properties as components of wood-plastic composites and to investigate the properties of the wood-plastic composites produced. The overall objective was to test the potential of available alien plant species as raw material for the manufacture of products. This would contribute to sustainability and give them a better chance of ending their life cycle. One of the possible solutions on a large scale is to use alien wood species for the production of wood plastic composites (WPC). Five invasive alien hardwood species have been used in combination with polyethylene powder (PE) and maleic anhydride grafted polyethylene (MAPE) to produce various flat pressed WPC boards. Microstructural analyses (confocal laser scanning microscopy and scanning electron microscopy) and mechanical tests (flexural strength, tensile strength) were performed. Furthermore, measurements of density, thickness swelling, water absorption and dimensional stability during heating and cooling were carried out. Comparisons were made between the properties of six WPC boards (five alien wood species and mixed boards). The results showed that the differences between different invasive alien wood species were less obvious in mechanical properties, while the differences in sorption properties and dimensional stability were more significant. The analyses of the WPC structure showed a good penetration of the polymer into the lumens of the wood cells and a fine internal structure without voids. These are crucial conditions to obtain a good, mechanically strong and water-resistant material.

Determining the optimum conditions for silane treated rubberwood flour-recycled polypropylene composites using response surface methodology

The objective of this work was to determine the optimum combination of two materials in production of wood-plastic composites, using response surface methodology (RSM). The two independent variables investigated were the wood content and the silane concentration. The experiments were conducted based on a central composite design. The findings showed that the wood content significantly affected the tensile and flexural properties of the composites as well as their water absorption and the silane concentration also significantly affected the water absorption of the samples. The optimum properties found by RSM were a content of 39.22 wt% wood, 60.78 wt% recycled polypropylene and a 3.44 % silane concentration. The findings from this work can be used to produce value-added and environmentally friendly panels for a variety of different applications.

Preparation of Sawdust-Filled Recycled-PET Composites via Solid-State Compounding

Recently, consumer markets have shown great interest in sustainable products. Considerable research efforts are headed towards developing biodegradable and recyclable polymers and composites. In this study, the fabrication of a wood–plastic composite (WPC) via solid state compounding has been examined. Polyethylene terephthalate (PET) and wood sawdust waste as major components of waste and challenging materials for the manufacturing of WPCs have been explored. Furthermore, the addition of poly(ε-caprolactone) as a biodegradable plasticizing agent was investigated. Composite powders were prepared by cryogenic solid-state milling (cryomilling) according to a statistical mixture design. Mechanical and water absorption properties were inspected on film samples obtained by hot pressing. Different formulations resulted in a variety of colors, textures, water interactions and mechanical properties. A sawdust content of approximately 25 vol.% was optimal for the best combination of properties. The results indicated that cryomilling is technically advantageous in the production of WPCs.